I read it once, not particularly carefully. Rather hurriedly in fact since I was at work at the time. I took "an expansion's worth of content" to mean "the amount of content one would expect to receive when paying for an Expansion Pack from ArenaNet". That qualifier is quite important, because to ArenaNet the word "Expansion" has a different meaning to that which it would have if Blizzard or SOE used it.
The only content release for ANet's other Guild Wars game that was ever described officially as "an expansion" was "Guild Wars: Eye of the North". Historically at least, in ANet/GW terms, an "expansion" is something less than you might expect. The previous additions to the elder game which were released as boxes through retail outlets were called "Campaigns". Those were stand-alone products incorporating the original Guild Wars. Because EOTN uniquely required that you already own a Guild Wars Campaign to play it, they used the term "expansion pack" instead.
You can already see how muddled this is. Developers, producers, players and commentators are throwing terms around without a common understanding of their definitions. That always leads to trouble. An "expansion" for EQ2 is a very different beast to an "expansion" for EVE, which is different again from one for Darkfall and round and round we go.
|Perhaps! I said "Perhaps"|
Using ANet's own established benchmark for "expansion", Eye of the North, it is not unreasonable to anticipate "new content for existing characters: dungeons, a number of new skills, armor" to quote from the GW1 Wiki.
The Wiki goes on to add " Eye of the North is set in previously inaccessible territory from the first Guild Wars campaign, Prophecies". From that we might hope to see the opening of some of the areas that we can currently see on the GW2 map of Tyria but cannot reach. That's certainly what I'm hoping for.
New races, classes, levels or entire new categories of gameplay such as you might expect to find in something caled an expansion from another MMO House (Wrath of The Lich King or Scars of Velious for example)? No, we won't be getting those.
The upshot of all this is that after a decade and a half it is still a bad idea to give games developers open access to the public.